Art of making metal-surface litho-grain printing-plates.



F. NIEMEYEH.

ART OF MAKING METAL SURFACE LITHO-GRAIN PRlNTING PLATES.

APPLICATION FILED AUG-22. I912.

Patented Dec. 7, 1915.

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FREDERICK NIEMEYER, 0F HOBOKEN', NEW JERSEY.

ART OF MAKING METAL-SURFACE LITHO-GRAIN PRINTING-PLATES.

Specification of Letters Patent.

Patented Dec. 7, 1915.

Application filed August 22, 1912. Serial No. 716,439.

To all whom it may concern Be it known that I, FREDERICK NIEMEYER, a citizen of the United States, residing in Hoboken, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in the Art of Making Metal-Surface Litho-Grain Printing-Plates, of which the following is a speci fication.

This invention relates to the manufacture of litho-grain metal printing plates, for use in printing by the lithographic method, and relates more particularly to the manufacture of litho-grain zinc plates for such uses.

A principal object of my present invention is to furnish an improvement in the art of producing such metallic printing plates in which the litho-grain surface of the completed plate will be produced through an acid-reduction of the plate mass to the extent of forming an undulating grain below the original plate surface; and concurrently subjecting the grain-surface, especially during the last stage of the grainforming period, to the action of a modifiersubstance containing as one of its ingredients or components, a metal different from the metal of the plate and adapted to be so far or so much released during the period of the acid-reduction as to effect a modification,in conjunction with the acid or other chemicals present during the acid-reduction,of the said grain-surface, or surfaceformation of the grain, when the plategraining operation comes to its final stage. ()f such metals, zinc is well adapted for the plate, while copper is suitable as a modifier-metal therefor; these two metals combine or directly associate together to form a metal different from either one alone, and I have discovered that some of these compositions are particularly suitable for the grain-surfaces of metal lithographic printing plates.

A process for litho-graining metal plates and adapted for producing the herein described metal-surfaced, uncoated litho-grain zinc printing-plates, forms the subject-matter of my concurrently pending application, Serial No. 679,745, filed Feb. 24, 1912, and allowed May 4, 1912. Certain improvements in printing-plates which are in part disclosed in my sald prior application, No. 679,745, and certain features which are set forth in my present application, are also set forth and are claimed in my other application, Serial No. 716,438, filed Aug. 22, 1912, and concurrently pending herewith. And such other features of improvement in those processes and in the plates as produced thereby, as are set forth but are not claimed in those applications or herein, will form in part the subject-matter of other applications to be filed by me, and to be concurrently pending herewith In the accompanying drawing, Figure 1 is an enlarged and diagrammatic perspective view illustrative of a fragment of a lithograin printing plate made in accordance with my present improvements. Fig. 2 is a sectional view on a greatly enlarged scale for illustrating, in a diagrammatic manner, certa n features and characteristics of a printing plate made in accordance with the improvements which are hereinafter more fully explained.

Similar reference characters designate like parts in all of the views.

In Fig. 1, the plate as a whole is designated by P, and the grain upon or forming its upper surface being indicated by n. The plate P is here shown of much greater thickness than is necessary in practice, While the grain n is only represented in a diagrammatic manner, which is further illustrated at n, Fig. 2; here the plate P is greatly enlarged in thickness. The line 3, Fig. 2, gives approximately the height of the original upper surface of the blank plate, so that the unshaded space at 4, below the line 3 and above the undulating line 5-5, indicates how the metal of the blank plate is dissolved away during the process of making thereon the litho-grain.

Below the grain-surface line 55, I have drawn the line 6 (also indicated in Fig. 1) parallel to the line 3, for indicating substantially the lower boundary of the grain-formation, so that the metal above the line 6 and below the line 5-5, may be said to form the body of the grain formation, except that the metal in a narrow sectional zone, as e, lying between the correspondingly undulating lines 5-5 and 7-7, may be said to constitute the surfaceformation, or the surfacezone of the grain-formation.

In Fig. 2, the sectional area is indicated by the short, inclined dashes, as at d, and these in the case of a zinc plate may be assumed to diagrammatically represent the atoms of zinc. In the narrow surface zone 6, however, round dots are interspersed with the dashes for similarly illustrating a. modified surface-formation in said zone 6 by means of another metal, (such, for instance, as copper when the plate body 1s zinc), the atoms of which are directly assoclated among the zinc atoms.

For making my improved litho-grain plate, I prefer .to follow, in a general way, a-proceduresubstantially such as described in my aforesaid application, Serial No. 67 9,745, but that procedure may be changed within the purview of my present invention. In the acid bath in \vhlch the blank plate is treated, I incorporate therein a modifiersubstance, preferably in theform of granules, which contains a metal other than the metal of the plate, this modifier-metal being chemically associated in the granules with another substance (such as an acid or gas) which, on being released, and so far as released from such chemical association in the granules, may operate directly or in connection with other substances as .a solvent for the metal of the plate on or to which the modifier-substance shall be applied during the process of forming the litho-grain on the plate. In practice, when the plate is put in the bath, this being preferably of dilute nitric acid, the: modifier granules may be applied or spread thereon in a thin layer in any convenient manner. Ihe said granules or modifier-substance is thus subjected to a dissociative action while in contact with and concurrently with the dissolving away of those zinc atoms which are removed to form the grain-structure, so that the result ant modified surface is not only grained and brought into a roughened and undulatory shape or form, but the modified part or surface normally follows over and conforms to those undulatory surfaces or forms, and thus gives to the plate a distinct and improved character.

In some cases the modifier-metal may consist of more than one individual metal, as, for instance, a combination of copper and iron, and these may be associatedwith a single gas, as cyanogen; and this composite modifier-metal may be used in connection with plates made of zinc, the cyanogen when released from its association with said modifier-metals being operative, in a well known manner, for the dissolving of zinc. One feature of copper as a modifier-metal for use in connection with zinc plates, is the facility with which this metal alloys with the metal of the plate in varying proportions, so that in practice a peculiar combination may be formed between the modifiermetal and the surface-formation of the grain, in which the'zinc in such surface portion may combine with a small proportion of the copper, and may do this in a combination having the nature of an alloy-union, thus distinguishing such combination from the usual merely deposited coatings, or surbrassified takes and retains the substance of the artists crayon with peculiar facility, and also readily receives and properly retains the necessary amount of water or moisture while the plate is in use.

While I have herein particularly described-my present improvements as applied to litho-graining plates of zinc,since in practice this is one of the principalmetals employed in making printing plates,it will beunderstood that the broader features are applicable to the making of litho-grain on plates of copper, iron, aluminum and other metals, by the employment of suitable plate-reducing acids in connection with a modifier-substance containing a modifiermetal having a proper relation to the selected plate-metal, and which is initially combined with a corresponding plate-metal solvent. When the plate-metal is of zinc one suitable, and usually the preferable,-

modifier-substance will be one containing copper as the modifier-metal, this copper being initially combined with a suitable or corresponding plate-metal solvent, and one such solvent with which the copper may be initially combined is cyanogen, which, within the purview of my present improvements, may also be accompanied 'by other substances directly associated in the initial combination with the copper. An instance of this kind of modifier-substance yielding copper is a double cyanate comprising copper and another metal, such as, for instance, iron; and, in practice it is not of material importance whether the copper yielding modifier-substance shall be entirely free of materials other than those here specified, since moderate proportions of various materials may be mixed or incorporated with the proper or selected modifier-metal, without seriously impairing the proper action of the same during the acid-reduction of the platemetal to the degree of forming the lithograin of plate-metal which was initially within the body of the plate and below the original surface thereof.-

When copper is chemically associated with a zinc-solvent, such for instance as cyanogen, (as in a cyanate, for instance) in small granules which are in contact with zinc and are there subjected to dissociation in a nitric acid bath, it appears that while the coppermeager granule is attacked by one (the nitric) acid, the zinc is attacked not only by the acid but also by the copper-holding zinc-solvent instantly as released from the granules by the aid of the acid. Also, it appears probable, as l'now apprehend, that any such attacking zinc-solvent, in leaving the copper may join in helping to dissolve the zinc, and may tend to carry some copper atoms into union with some zinc atoms not then fully dissolved or displaced, but only incipiently so, and thus bring about a direct association of some copper atoms with sulficient zinc atoms for effecting the desired protective modification of the undulatory grain-surface; and these actions and re-actions appear, in my view, to involve the principle and phenomena of catalysis, but in some manner which, so far as I am now aware, is not yet fully known. Thus as I now apprehend, the relatively nascent atoms of the zinc and of the said other metal, in part unitein the surface of the plate, in some manner which, (though not yet fully known) appears to be analogous to alloying. In practice thissurface may be of an extremely small depth, and yet be a solid metal surface free of any coating, and essentially of the nature of an alloy. The chemical-action, and re-actions which occur during the process may, as I now deem probable, include such as are designated as a ring, particularly when the granules are a double-salt.

If" in the operation of making the litho-.

grain on a zinc plate with the aid of granules yielding copper, there should be some deposition of copper on the grain-surface at the time the grain hasreached the desireddepth, or size and character, such deposi -zinc plates by my improved process, is the 7 production of such a surface that after the picture has been transferred thereto, the usual picking up of flakes and other debris by the inking roller when the workman proceeds to roll up the plates, is avoided. -A further advantage is that a minimum quantity of water may be used, and this may be ap lied b a less moist roller, since the modifie meta surface of a zinc plate holds the v moisture with extreme evenness, andrthus favors the printing operations, especially when running on high-class work,

While the granules of modifier-substance will, of course, in practice, be constantly present in the bath, as the means (as more fully described in my said prior application, since issued as Patent No. 1045068, dated Nov. 19, 1912,) for regulating the grain-formation during the mass-reduction of the plate to make thereon the required metal-surfaced grain, the metal-modifying efiect whichv exists in the so formed and completed metal-grain, is evidently only so much of said effect as takes place near the later or final stage of the process, since prior an acid bath, suspending copper-yielding grains in said bath which gradually precipitate onto the plate, the acid etching .into the exposed surface of said zinc plate between the copper yielding grains to form an undulatory surface, and simultaneously with the formation of such undulatory surface, the'copper being freed alloying with the zinc included in the undulatory surface being formed, the process being continued only sufliciently long to form an undulated surface composed of an alloy of copper with the zinc of the plate proper.

2. A process for making on metal lithographic plates an undulatory all-metal surface, consisting insubjecting a surface of the plate to an acid bath, suspending metal yielding grains in said bath which gradually precipitate onto the plate, the acid etching into the exposed surface of said zinc plate between the metal yielding grains to form an undulatory surface, and simultaneously with the formation of such undulatory surface, the metal being freed from the grains alloying with the metal included in the undulatory surface being formed, the process being continued only sufficiently long to form an undulated surface composed of an alloy of copper with the zinc of the plate proper.

I FREDERICK NIEMEYER. Witnesses:

Jo n: Moms,

H. I). Penney.- 

